The present invention relates in general to methods and apparatus for verifying or authenticating an object that emits light. More particularly, the present invention relates to verifying or authenticating an object by determining its decay time constant at a predetermined temperature.
Disk drives for receiving removable disk cartridges, including conventional 3.5 inch floppy disk drives, must have some mechanism for detecting the insertion or presence of a disk cartridge in the drive. The actuator that carries the recording heads of the disk drive across the recording surfaces of the disk should not be allowed to move unless the presence of an appropriate disk cartridge which is non-drive damaging is detected. The removability feature requires that the disk drive have a cartridge insertion opening into which foreign objects can be inserted. If these objects physically engage the drive as a legitimate cartridge would, then the heads could be loaded onto or into the foreign object, thereby destroying the drive. Also, the spindle motor of the disk drive will be activated by a falsely detected foreign object, thereby generating particle debris. In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge within the drive. Such switches are typically positioned such that when a disk cartridge is inserted fully into the drive, the cartridge contacts the switch, thereby providing an indication that the disk cartridge is present.
The ability to discriminate between cartridge types after insertion into a data storage drive but prior to putting the read/write heads on the recording media is of significant value and utility. Principally this utility comes from the ability to detect the difference between various capacities or generations of data storage cartridges in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made such as media rotation rate, data channel rates, location of Z track for initial seeking, or even mechanical adjustment in the drive such as the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/generation of data storage cartridge inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
Recently, in various industries such as the distribution industry, phosphors have been used in the control of goods by means of bar codes, and furthermore, bar codes are printed on various prepaid cards and passing cards, and these bar codes are read by optical reading apparatuses, such as scanners, to perform the desired actions. Moreover, various attempts have been made to apply forgery prevention means to credit cards and prepaid cards or to detect forged cards. For example, the marks such as bar codes are printed with an ink containing a phosphor by offset printing or by using an ink ribbon to form latent image marks. The latent image marks are irradiated with a semiconductor laser beam to excite the phosphor and the light emitted from the phosphor is received to read the bar code information by an optical reading apparatus. These techniques use the content or spectral shift from the irradiating light source for identification.
Pending U.S. patent application Ser. No. 09/161,007, filed on Sep. 25, 1998, which is a continuation-in-part application of U.S. patent application Ser. No. 08/936,970, filed on Sep. 26, 1997, both of which are incorporated herein by reference, describes a latent illuminance marker and systems and methods for using the decay time constant of the marker to identify, verify or authenticate the object that the marker is attached to. A latent illuminance marker having a particular decay time constant is attached to an object to be verified. Light is illuminated on the marker, and then turned off. The decay time constant of the material in the marker is measured and compared to a predetermined value. If the measured decay time constant equals the predetermined value, then it is determined that the object is identified, verified, or authenticated.
However, some latent illuminance markers can exhibit the predetermined decay time constant at the standard operating temperature (e.g., at room temperature, during normal use, in a disk drive) but do not have the desired characteristics (material properties) of a true or authentic marker, such as the desired decay time constant, at non-operating temperatures. In other words, non-authentic markers can exhibit the correct decay time constant at the standard operating temperature, although they do not have the other characteristics of an authentic marker. Thus, these markers cannot be trusted to be authentic markers or markers having the true desired characteristics, which could lead to reliability problems, for example, such as the misidentification of the object to which the marker is, or will be, attached.
The present invention is directed to systems and methods for identifying a type of material in a marker having a temperature, comprising: a temperature altering device for setting the temperature of the material to a predetermined temperature; a light source for emitting light to illuminate the marker; a photodetector for measuring an intensity of light received from the marker; and a microprocessor for determining a decay time constant of the material responsive to the intensity and for determining the type of material responsive to the decay time constant at the predetermined temperature.
According to further aspects of the present invention, a comparator compares the decay time constant to a predetermined decay time constant to produce a comparison result wherein the microprocessor determines the type of material responsive to the comparison result.
Another embodiment within the scope of this invention includes systems and methods for verifying the authenticity of an object having a marker disposed thereon, the marker comprising a latent illuminance material, comprising: a temperature altering device for setting the temperature of the latent illuminance marker to a predetermined temperature; a light source for emitting light to illuminate the marker; a photodetector for measuring an intensity of light received from the marker; and a microprocessor for determining a decay time constant of the latent illuminance material responsive to the intensity of the light and for verifying the authenticity of the object responsive to the decay time constant at the predetermined temperature.
The foregoing and other aspects of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.